A clinical questionnaire concerning anorectal symptoms and urodynamic tests was used to investigate 409 women consulting for stress urinary incontinence. To compare urodynamic data, patients were divided into three groups of women who had either stress urinary incontinence associated with incontinence for formed and/or liquid stools or with gas incontinence, or isolated stress urinary incontinence. To take in account the patients'age for data interpretation, a Mantel-Haenszel test or covariate analysis was performed. Anal incontinence was reported in 114 (28%) of the 409 women investigated. The prevalence of incontinence for gas only, for liquid, or for solid stools was 18.3, 9.3, and 1%, respectively. The duration of gas incontinence was longer than that of fecal incontinence or stress urinary incontinence. Difficult defecation was more frequently observed in patients with double incontinence than in patients with only stress urinary incontinence, and the difference was significant between patients with gas incontinence and patients with stress urinary incontinence (53% versus 37%, P = 0. 03). There was no difference in the number of bowel movements per week among the three groups of patients. The number of vaginal deliveries was surprisingly lower in patients with fecal incontinence associated with urinary incontinence than in others. There was no urodynamic feature that could distinguish patients with urinary incontinence and patients with double incontinence. This study confirmed the close relationship between anal and stress urinary incontinence. Neurourol. Urodynam. 18:579-590, 1999.